Spa



FIG. 1 is a left perspective view of a spa showing the design;

FIG. 2 is a right perspective view thereof;

FIG. 3 is a front view thereof:

FIG. 4 is a rear view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a right side view thereof;

FIG. 7 is a top view thereof; and,

FIG. 8 is a cross-sectional view thereof taken along line 8-8 in FIG. 6 to better show the details of the interior of the spa.

The broken lines depict portions of the spa that form no part of the claimed design. 

CLAIM The ornamental design for a spa, as shown and described. 